Use of a mirror has been indispensable to applying makeup or shaving. A plane mirror is generally used for those purposes, but a concave mirror may be used for magnification.
To this end, a double-sided mirror having a plane mirror on one side and a concave mirror on the other side has been used as a mirror for washrooms in hotels or the like for a long time.
Patent document 1 discloses a hand mirror comprising a flexible mirror sheet secured at its peripheral edge to a frame, a support rod fixed to the mirror sheet at its center, an operating handle mounted on the frame for rotation, and an adjusting mechanism for moving vertically the support rod relative to the flexible mirror sheet when the operating handle is rotated, the vertical movement of the support rod permitting the flexible mirror sheet to be deformed, thereby varying curvature of the flexible mirror sheet and thus, changing from a plane mirror to a concave mirror, or from the plane mirror to a convex mirror. In patent document 1, a delicate difference in curvatures is made at a point where a force is exerted directly on the mirror sheet and at a location where no force is applied to the mirror sheet to result in distortion of the mirror face. In addition, the disclosed mirror has the disadvantage that, due to the fact that curvature is varied mechanically, the variations of curvature are stepwise effected and therefore, it is hard to select any suitable curvature.
Non-patent document 1 discloses a technology to utilize, for a large-scale reflector, a flexible mirror sheet sealedly retained at its periphery and deformed into a concave mirror or convex mirror by gaseous pressure. According to this technology, there is a difference from the mirror disclosed in Patent document 1, in that a negative or positive pressure is applied to the mirror sheet to vary its curvature and therefore, the mirror has no distortion, and variations of curvature are continuously effected. However, a large-scale pressurizing or pressure reducing device is required to apply gas directly to the mirror sheet and therefore, this technology cannot be applied to a hand mirror.